iFixit gives a rare look inside a factory that makes phone batteries

Have you ever wondered what actually goes into making it? batteries for your smartphone? New Behind the scenes video by iFixit Pulls back the curtain on how iPhone replacement batteries are really made and takes us straight to the factory in Weao, China, where around 13 million smartphone battery cells are produced every month.

While a smartphone battery may look like a simple package of solid chemicals from the outside, turning a raw lithium-polymer cell into a fully functional, device-ready component requires rigorous precision engineering, software, and rigorous quality control.

The battery manufacturing process begins with the lithium-polymer cell itself, which consists of dozens of folded, ultra-thin layers assembled to microscopic tolerances.

However, you can’t just apply raw electricity to these cells – you can, but it’s extremely dangerous, high-risk, and not recommended on a scale for everyday use. A good battery setup requires a special Battery Management System (BMS) board to safely regulate power.

At the factory, a series of blank BMS boards are attached to a special programming machine that runs the necessary safety software to prevent dangerous overloads and overdischarges. After programming, the BMS board and its connecting cable are soldered directly to the raw cell.

The BMS folds neatly over the camera to ensure a compact footprint that fits inside a modern iPhone. To prevent catastrophic short circuits during this folding process, technicians apply special tape to the edges before sealing the final, folded assembly with an outer sticker.

Any finished battery must pass a rigorous quality control inspection before leaving the factory floor. Special diagnostic machines test each battery for internal impedance, total capacity and overcurrent safety limits. In addition, the BMS is electronically read to verify key metrics, such as setting the initial health status to 100% (or slightly higher) and confirming that the design capability meets Apple’s strict requirements.

The final touch before packaging involves the application of the infamous sticky adhesive strips, turning the raw cell into a familiar battery ready to power your next device. The video provides a fascinating look at a piece of technology that we often take for granted, so check it out!